Hydrothermal carbonisation of digestate: An investigation ...
Understanding and marketing digestate - WRAP and marketing... · Understanding and marketing...
Transcript of Understanding and marketing digestate - WRAP and marketing... · Understanding and marketing...
Understanding and marketing digestate
Matt Taylor, ADAS
David Tompkins, Aqua Enviro
Scope of this course
Our focus is on:
Land/soil-based markets
Digestates certified to PAS110
The following are out of scope:
Marketing of digestate fibre for combustion
Marketing of fertiliser products extracted from digestates
Marketing of other ‘added value’ digestate extracts
Completing natural nutrient and carbon
cycles
Why digestate?
Overview of digestate benefits
What are the main benefits?
1. Nutrients– N, P, K, S, Mg– Trace elements
Users are most interested in crop available nitrogen
2. Organic matter (fibre)– Soil physical quality Available water capacity Workability Drainage
Save money
Reduce carbon footprint
MT
Overview of digestate benefits
Livestock slurry values taken from “The Fertiliser Manual (RB209)”
Food-based digestate adapted from Taylor et al. (2010)
Overview of digestate benefits: nutrients
Typical nutrient content of food-based digestate and livestock slurries (kg/m3)
High readily available N >30% total N (NVZs) RAN Organic N
Food-based digestate
70%Pig slurry
Cattle slurry
Green compost
Green/food compost
<3% 5%
80%
45%
Readily-available N (ammonium-N) [potentially crop-available]
Overview of digestate benefits: nutrients
Units Cattle slurry
Manure-
based
digestate
Crop
(maize)
based-
digestate
Fibre crop
(maize)
based-
digestate
Application ratet/ha or
m3/ha30 30 30 40
Norfolk experimental site
Dry matter % 7 5 8 16
pH 7.8 8.2 8.1 8.3
Total N kg/ha 90 98 142 230
Ammonium-N kg/ha 52 59 77 6
Gleadthorpe experimental site
Dry matter % 7 8 8 22
pH 7.5 8.3 8.3 8.5
Total N kg/ha 91 112 180 270
Ammonium-N kg/ha 56 59 163 121
Overview of digestate benefits: nutrients
MUST be product (batch?) specific
Organic matter additions
Whole digestate (or separated liquor) applies very little organic matter
Three years of additions as part of DC-Agri applied c.2 t/ha of organic matter –a single compost/FYM addition applied >5 t/ha (based on 250 kg N/ha application)
Fibre digestate is a valuable source of stable organic matter, applying c.5 t/ha of organic matter (based on 250 kg N/ha application)
Overview of digestate benefits: organic matter
Potential carbon savings – whole digestate
NutrientCO2e (kg CO2e /kg
nutrient)
Food-based digestate nutrient content (kg/m3)
CO2e (kg/t) saving
Crop available Nitrogen
6.2 3.0 18.6
Total phosphate-P2O5
0.7 0.5 0.4
Total potash-K2O 0.5 2.0 1.0
Total 20.0
CO2e figures from Brentrup and Paliére (2008)Based on crop available N = 60% of total N applied
Overview of digestate benefits: carbon savings
Digestate properties
Liquid – it flows and is heavy!
Limited application windows
Not ‘odourless’
Need to secure local landbank
Digestate is:
– expensive to transport
– awkward to store
Perceptions around waste status and safety/quality
Key issues in recycling digestate to land
Non-agricultural markets
OMK004 – landscape and regeneration
Biomass crops on landfill (SRC, miscanthus)
Energy crops on landfill (rye grass, biodiverse mixes)
Soil manufacture
Sports turf
OMK006 – horticulture
Fertiliser in containerised nursery stock
Growing medium (fibre digestate) for nursery stock and vegetable transplants
Fertigation of table-top strawberries
Hydroponic production of salad crops
Non-agricultural markets for digestate
Digestate can work in these markets, but there are challenges
Regulations
– Many uses not covered by AD Quality Protocol or Standard Rules Permits
Chemical
– Electrical conductivity can be high; some crops need nitrate instead of ammonium; odour may be intolerable in some markets
Physical
– Bulky (compared to conventional alternatives); suspended solids can clog application equipment; physical contaminants may be intolerable in some markets; heavier than growing media alternatives; water-holding in fibre digestate poorly understood
Non-agricultural markets for digestate: Summary
Financial
– High value of crop vs low cost of nutrients (and hence low value of digestate)
– Land restoration operators expect to be paid
Biological
– Human and plant pathogens must be demonstrably absent
Inherent variability of material
– May need bespoke approaches for each AD site
Need to stabilise fibre before use in growing media
Separating out fibre still leaves majority of volume behind
Non-agricultural markets for digestate: Summary
Farmers need: A reliable service
– Digestate delivered and spread when needed
– Confidence
– They can make adjustments to fertiliser application rates with confidence
– Use of the product will not adversely affect their business
Communication
– Sufficient information is provided for farmers to make decisions quickly and easily
– Any concerns are addressed promptly
Assurance
– There will be no issues with selling their produce
– Using digestate can add value to their business
Quality
– A product which will not contaminant their land or harm their crop
Providing a service to farmers
ALOWANCE landbank estimator
http://web1.adas.co.uk/alowancehome/
Providing a service – estimating available landbank/market size
Different crops have different nutrient requirements
Providing a service – estimating available landbank/market size
Crop nutrient requirements vary through the year
Grassland may offer multiple spreading windows
Oilseed rape has an autumn nitrogen demand
There are various tools to help –including the RB209 fertiliser planning manual
https://www.gov.uk/government/publications/fertiliser-manual-rb209
How can we assess nutrient content?
Standard values??
– Effect of:
– Different feedstocks
– Post-digestion processes
– Where do you look?
Measure it!
– Laboratory analysis
– Rapid on-the-spot analysis
– Quantofix
– Agros
Providing a service – understanding nutrients in digestate
Total, readily available or crop-available?
Providing a service – understanding nutrients in digestate
Essential to understand difference, as this impacts on crop nutrient planning and the price you can charge for digestate
Total Readily available Crop-available
Livestock slurry values taken from “The Fertiliser Manual (RB209)”
Food-based digestate adapted from Taylor et al. (2010)
Total nutrients (kg/m3)
Providing a service – understanding nutrients in digestate
High readily available N >30% total N (NVZs) RAN Organic N
Food-based digestate
70%Pig slurry
Cattle slurry
Green compost
Green/food compost
<3% 5%
80%
45%
Readily-available N (ammonium-N) [potentially crop-available]
Providing a service – understanding nutrients in digestate
Overall cross-site N-use efficiency
Providing a service – understanding nutrients in digestate
There are tools to help…
www.planet4farmers.co.uk
Providing a service – understanding nutrients in digestate
End of waste for defined source-segregated biodegradable wastes
Two parts:
– Anaerobic Digestate Quality Protocol
– Approved specification (PAS110)
If an operator complies with both and is independently certified to both, then the biofertiliser is no longer a waste and can be used as a product
http://www.biofertiliser.org.uk
End of waste for digestate in E, W & NI
Providing a service – understanding Codes of Practice and Regulations
Agriculture and forestry and soil/field-grown horticulture
Quality separated fibre only may be used for land restoration
Use of digestate as a growing medium and for amateur or hobby gardening and similar uses is specifically prohibited
http://www.biofertiliser.org.uk/adqp
End of waste for digestate in E, W & NI
Providing a service – understanding Codes of Practice and Regulations
End of waste for digestate in Scotland
http://www.biofertiliser.org.uk/pdf/SEPA-Position-Statement.pdf
Providing a service – understanding Codes of Practice and Regulations
Cost waste route vs product route
Providing a service – understanding Codes of Practice and Regulations
Legal ban on grazing (or harvesting herbage for feed) land treated with ABP-derived digestates
You must alert users to this when supplying digestate (keep a paper trail)
In England the grazing ban is 8 weeks for pigs and 3 weeks for all other farmed animals
Check with APHA whether need to register to haul digestate
User of digestate needs to keep records of their use to demonstrate grazing/harvest ban compliance
Using digestate: ABPR
Providing a service – understanding Codes of Practice and Regulations
Supplying digestate to Organic farms
What they can accept is covered by Regulation (EC) 889/2008
Annex I lists accepted inputs, including digestate
– Can only be derived from ‘household’ food waste
– PTE limits are different to PAS110
Annex I was amended in 2014, but no guidance yet agreed
– ‘Not of factory farming origin’
– Farmers should consult with their Organic CB before accepting digestate
– It is in your interests to ensure this happens (fit-for-purpose)
Providing a service – understanding Codes of Practice and Regulations
NVZs – organic manure N field limit
In each field, in each 12 month period: no more than 250 kg N/ha of total N from all organic manures
– includes digestate, composts, biosolids, FYM etc.
Providing a service – understanding Codes of Practice and Regulations
NVZs – Nmax
Crop available N from all organic manures now count towards Nmax
No ‘standard figures’ for digestate, so have to provide evidence:
– MANNER-NPK
Providing a service – understanding Codes of Practice and Regulations
NVZs – closed spreading periods
Applies to all soil types and all organic manures with a high readily available N content
– defined as over 30% of the total N content
– e.g. slurry, poultry manure, food-based digestate (potentially even fibre digestate)
Providing a service – understanding Codes of Practice and Regulations
NVZs – closed spreading periods
Grassland Tillage land
Sandy or shallow soils
All other soils Sandy or shallow soils
All other soils
1 Sept – 31 Dec
(4 months)
15 Oct – 31 Jan
(3½ months)
1 Aug – 31 Dec*
(5 months)
1 Oct – 31 Jan
(4 months)
*Tillage land: On sandy or shallow soils, application is permitted between 1 Aug and 15 Sep inc., provided a crop is sown on or before 15 Sep
From end closed period until end of February, no more than 30m3/ha of slurry or 8 t/ha of poultry manure in a single application and no repeat applications within 3 weeks
Providing a service – understanding Codes of Practice and Regulations
Some farmers may not have manure risk map
Codes of Good Agricultural Practice/cross compliance
Providing a service – understanding Codes of Practice and Regulations
Nutrient and financial value of a ‘typical’ food-based digestate application (30 m3/ha)
Food-based
kg/ha £/hab
Crop available Na 90 81
Total phosphate 15 10
Total potash 60 27
Total £118
aAssuming spring bandspread application
bAssuming N = 85 p/kg, P2O5 = 65 p/kg, K2O = 45 p/kg
Providing a service – addressing myths and risks: digestate value
Financial issues
Spring bandspread application worth c.£4/m3
– Transport £3/m3 (based on 10 miles)
– Application £3/m3 (based bandspread)
Therefore…
Need to maximise value to break-even (demonstrate value to farmer)
But…
Autumn bandspread application worth c.£1.50/m3
Providing a service – addressing myths and risks: digestate value
Source: Taylor et al. (2010); Defra “Metals in Soils” project
0.0
1.0
2.0
3.0
4.0
Food-based
digestate
Cattle slurry Pig slurry
kg
/ha
/yr
Zinc
Copper
Metal loadings to soil
Providing a service – addressing myths and risks: digestate quality
Source: Taylor et al. (2010); Defra FIO-FARM project
0
40000
80000
120000
CF
U (
g/f
w)
<10
Food-based
digestate
Manure-based
digestate
Pig
slurry
Cattle
slurry
2700
[ABPR/PAS 110 upper limit 1000 CFU/g FW]
E. coli
Providing a service – addressing myths and risks: digestate quality
Film plastic in digestate
Providing a service – addressing myths and risks: digestate quality
PAS110 limits may not meet the demands for all markets
This can apply to a range of digestate parameters, not just plastics:
– Stability
– PTEs
Source: Taylor et al. (2010); Defra Water Code (1998)
0
5000
10000
15000
20000
25000
30000
1 2 3 4 5
BO
D (
mg
/lit
re)
Manure-based
digestate
Food-based
digestates
Cattle slurry* Pig slurry* Dirty water*
BOD (biochemical oxygen demand)
[‘Typical’ sewage works discharge consent = 20 mg/litre]
Providing a service – addressing myths and risks: digestate quality
“Confidence in digestate”
Risk-based guidance for the use of source-segregated anaerobic digestates in GB agriculture
Project code OAV036-008
Providing a service – addressing myths and risks: digestate safety
Other relevant work
Providing a service – addressing myths and risks: digestate safety
Check WRAP website for publication
Bandspreading/shallow injection reduces ammonia
losses and odour nuisance
Trailing hoseSurface
broadcast
Precision spreading
Providing a service – different spreading techniques
Digestate storage
Digestate needs to be applied at the correct time (legal restrictions plus beneficial use)
Therefore storage is required, but:
– Where? (site production, on farm)
– How much? (landbank dependent)
– How? (uncovered, aero cover, fixed)
Providing a service – digestate storage
Overall – how to market digestate to farmers
Highlight digestate benefits
Address any objections
Consider the local landbank
Work out the logistics
Use the local farming community
Target appropriate farm types / farmers
Build a business model and marketing plan
Roll it out!